The present invention relates to a sensor-equipped radio terminal device.
Conventionally, the device for detecting an object to be detected has been used in an environment supplied with power all the time. Accordingly, there has been no problem in consuming a large amount of power. However, when the device for detecting a detection object all the time is made with a small size for wireless use, for example, a battery is arranged as a power source and the battery service life makes it difficult to supply a large amount of power all the time.
To cope with this, there is considered a method for operating intermittently instead of continuous operation of the device detecting a detection object. When the device detecting a detection object performs intermittent operation, the device is in a wait state during a non-operation period, i.e., the device can suppress power consumption during that period as compared to the normal operation period, thereby reducing the entire power consumption.
A device for suppressing power consumption by intermittent detection is disclosed in JP-A-2003-16566. That is, a first switch connected to a detection unit is turned ON at a predetermined time interval and a second switch is turned ON only if the detection signal value exceeds a threshold value, thereby performing a radio transmission.
When suppressing the power consumption by using the intermittent operation, the interval between the intermittent operation should be as long as possible. However, as the interval between the intermittent operations is increased, the detection of a detection object is delayed.
Moreover, in order to reduce the delay of the detection of the detection object during intermittent operation, the interval between the intermittent operations should be reduced. That is, in the intermittent operation of the device for detecting a detection object, the power consumption and the detection response are in the trade-off relationship.